One of the deadliest infectious diseases on the planet, which is caused by Ebola virus (EBOV), may relapse, researchers have warned. A study, published on Wednesday and dubbed “groundbreaking” by the scientific community, has found that Ebola may be hiding in the brain of those thought to have recovered years ago following an antibody treatment.
Such persistent infections in survivors make them spread the virus again, “potentially causing a new outbreak,” according to researchers.
The study was conducted by a team at the US Army Medical Research Institute of Infectious Diseases (USAMRIID). Having linked some recent Ebola outbreaks in Africa to persistent infection in patients who had previously survived the disease, researchers aimed to discover where exactly the virus could be sitting in the body, avoiding antibodies. To locate the hiding virus, they used a nonhuman primate model, which most closely recapitulates Ebola virus disease in humans.
They discovered “severe inflammation and massive Ebola virus infection” in the brains of about one in five macaque monkeys that had received monoclonal antibody (mAb) treatment. The virus persisted specifically in the brain ventricular system, in which cerebrospinal fluid is produced, circulated, and contained. Despite being cleared from all other organs with effective therapeutics, the virus was able to re-emerge to cause lethal disease, while also severely damaging brain tissues.
“These findings have implications for long-term follow-up efforts to reduce the individual (disease relapse/recrudescence) and public health (reignition of outbreaks) consequences of viral persistence in survivors of EBOV infection,” the authors warned.
During some of the worst recent Ebola epidemics in west Africa, more than 28,600 cases were reported between 2013-2016. More than 11,300 patients died, but the survivors could still harbor the virus and pass it on. Last year, an outbreak of Ebola virus disease in Guinea was linked to some cases of persistently infected patients, who survived a previous major outbreak at least five years ago. However, the exact hiding location of the virus in the body was unknown at the time.